| With the upgradation of the national electric power grids,the new generation of power system continues to develop.The structure and how to operate the distribution network become more and more complex and polytropic,which brings new challenges to the distribution network scheduling,analysis,and planning.Line loss is an important technical and economic metric for power grid enterprises.The basis of line loss management is to find out the relationships between distribution lines and transformers.The topology of medium voltage distribution network in power system describes the interconnection among medium voltage feeders,distribution transformers,and interconnection switches.However,the operations on the feeders,such as troubleshooting and load reversal,are possibly to change the switch state,thus changing the operation topology.Caused by the human judgements and the delay of analysis methods,the operating topology of distribution networks is often inconsistent with the topology maintained in the system.The lack of accurate topology in operation state will increase the difficulty and potential risks when carrying out state estimation and the management of distribution network operations.Therefore,how to quickly and accurately identify the inconsistencies and give adjustment suggestions in a given topology in operation state is an urgent problem in the distribution network management.Based on the above requirements,this thesis designs and implements a topology diagnosis system of medium voltage distribution network,which can effectively help power analysts identify the connection errors in the network topology,and give adjustment suggestions based on multiple perspectives.The system is based on the following idea.We transform the topological connection problem of distribution network into a linear regression problem,calculate the correlation coefficient between the real voltage value and the fitted voltage value,set a threshold to determine whether the topology is wrong or not,and finally give an error correction scheme according to both the line connection and the set of feeders based on longitude and latitude.The proposed system is thus able to achieve the reliable and accurate identification of the operation topology of distribution network.The successful identification lays the foundation for various power network analyses,calculations,and advanced applications.Specifically,the work of this thesis is summarized as follows:1.Data cleaning,noise smoothing,clock synchronization and other preprocessing operations are carried out for the voltage data,and the power data of feeders and distribution transformers.2.The formula of distribution network topological connection is derived based on the power flow theory.Considering the characteristics of voltage and power,the problem of distribution network topological connection is transformed into a linear regression problem.Based on Bayesian information criterion,the threshold of correlation coefficient is established.Meanwhile,the correlation coefficient of interconnection feeder,bus,and the set of similar longitude and latitude feeders is calculated.3.We design and implement the web-based visualization system by using Spring Boot,Mybatis-Plus,etc.to implement the back-end of the system.We then use Vue and Echart to implement the front-end of the system to display the feeder account,line loss information,power stacking diagram,etc.in real time in the web page.The Jiangsu Electric Power Research Institute has collaborated with the Yangzhou Power Supply Company and the Xuzhou Power Supply Company to analyze some of the typical abnormal lines with related suggestions based on the proposed system.The feedback from these companies shows that the system identifies and corrects error connections well,improves the work efficiency of analysts in the local companies,and meets the requirements of practical application.This system has been applied to multiple power supply companies in Jiangsu Province at present. |
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